Below the Cliff House on the city's western edge, the concrete bones of San Francisco's grandest Gilded Age folly survive as a strange seaside ruin. Walk down from the parking lot above Point Lobos Avenue: the foundations of seven pools, the inlet that filled them with seawater at high tide, the tunnel that leads through to a hidden cove with a clear view of the Pacific.
It is one of the most evocative spots in the city — half nature reserve, half archaeology, with sea lions barking offshore. Sunset is the standard time to visit. Bring a torch if you want to walk the tunnel.